depending on size/weight of monitor, it's usually a good idea to get an arm that will support more than what your monitor is. your 27 is at the top of the supported list of this arm. so your 27 should be in the middle of the supported sizes notation. it's not only the size & weight of the monitor but the length of the arm segments. if you're at the top end of the scale you might have slightly limited movement due to length of arm segments... if that makes sense....
i finally picked up a tri-monitor stand not long ago and learned this while i was researching. the one i got is noting fancy, but does the job well and i'm happy with it. main/center monitor is 23", and sides are 17" & 15" (old dell screens)
what's your setup like? do you have a wall behind your desk? would it be easier to get the distance you want by mounting your screen on the wall instead of the desk? and pull your desk out from the wall a bit? (especially wanting the monitor further away than the desk is deep)